1. Field of the Invention
The present invention relates to an optical pickup unit capable of reproducing data recorded on a medium such as an optical disc and recording data onto the medium, and to a method of manufacturing the optical pickup unit.
2. Description of the Related Art
FIG. 11 is an explanatory view of one form of a conventional optical pickup unit.
The optical pickup unit generally designated at 501 is used to perform reproduction or recording of data such as information on a medium not shown. The medium can be e.g., an optical disc not shown such as a CD (Compact Disc).
Current is supplied from a laser driver 530 to a laser diode 540 so that laser light is issued from the laser diode 540. Laser means e.g., one utilizing dielectric emission for amplification of light. Laser is an abbreviation of “light amplification by stimulated emission of radiation”. The laser diode is abbreviated to “LD”. The laser driver 530 serves as a laser driving circuit 530 that drives the LD 540 for emission of laser light therefrom. Thus, the laser driver is called “LD driver”, etc., and is abbreviated to “LDD”. The LDD 530 supplies the LD 540 with current so that information is recorded on a disc 900 or information recorded on the disc 900 is reproduced by the action of laser light emitted from the LD 540.
Laser light from the LD 540 is applied via a diffraction grating 560, an intermediate lens 570, a half mirror 600, and an objective lens 710 to the disc 900. The diffraction grating 560 utilizes diffraction of light to divide laser light issued from the LD 540 into several beams of light not shown.
The half mirror is abbreviated to “HM”. The objective lens is abbreviated to “OBL”. The OBL 710 serves to condense laser light onto a signal portion 910 of the disc 900.
Part of laser light issued from the LD 540 enters a front monitor diode 650. The front monitor diode is abbreviated to “FMD”. The FMD 650 monitors laser light issued from the LD 540 to provide feedback for controlling the LD 540. Part of laser light reflected from the disc 900 impinges on a photo diode IC 820. The photo diode IC is abbreviated to “PDIC”. When receiving light, the PDIC 820 converts the signal into an electric signal to output a signal for operating a servo mechanism not shown of a lens holder 720 of the optical pickup unit 501. Servo or servo mechanism means, e.g., one or a mechanism measuring the status of an object to be controlled and comparing the measurement with a reference value to provide automatic adjusting control.
A housing 510 is disposed to house the LDD 530, the LD 540 the diffraction grating 560, the intermediate lens 570, the HM 600, the FMD 650, the lens holder 720 fitted with the OBL 710, and the PDIC 820. The housing means e.g. a box-shaped enclosure or an analogue to the box that holds components.
The LDD 530, the LD 540, the FMD 650, and the PDIC 820 are connected conductively to a flexible printed circuit 520. The flexible printed circuit is abbreviated to “FPC”. A process of fabricating the FPC will be described. A plurality of circuit conductors 520c in the form of e.g., metal foils such as copper foils are printed on an insulating sheet 520s such that the circuit conductors are juxtaposed on the insulating sheet. On top of the circuit conductors is disposed a protective layer not shown to form an FPC. The FPC 520 is formed as a two-layer flexible printed board or a so-called double-sided flexible printed board having the circuit conductors disposed on both sides of the insulating sheet.
The optical pickup unit 501 is configured to include the above various components. Although the optical pickup unit 501 includes other constituent elements not shown than the above shown, those constituent elements are not shown for convenience' sake in FIG. 11.
The FPC 520 is connected to the LD 540, etc., after which the LD 540 is mounted on the housing 510 while being positioned thereto.
Laser light from the LD 540 of the optical pickup unit 501 passes through the OBL 710 to impinge on the optical disc 900 such as a CD loaded in the interior of a player body. Information is recorded on the optical disc 900 or information recorded on the optical disc 900 is reproduced by the action of laser light issued from the LD 540. Recording or reproduction of information is thus performed by the optical pickup unit 501.
Another conventional optical pickup unit can be e.g., one capable of securely positioning a light emitting device and a light receiving device for mounting and of enhancing the effect of heat radiation without imparting unnecessary stresses to those elements (see, e.g., p. 3, FIGS. 1 to 5 of Japanese Patent Application Laid-Open Publication No. 2005-141821).
It was however a difficult work for the above conventional optical pickup unit 501 of FIG. 11 to securely mount the LD 540 on the housing 510 with high accuracy with the LD 540 being connected to the entire FPC 520. Although the FPC 520 is partially shown in FIG. 11 to facilitate understanding of the configuration of the optical pickup unit 501, the actual FPC 520 has a larger area extending to most of the housing 510.
When mounting the LD 540 on the housing 510, the LD 540 is fitted to the housing 510 while allowing the LD 540 to emit laser light. At that time, the entire FPC 520 connected to the LD 540 is obstructive, making it difficult to mount the LD 540 on the housing 510.
Execution of such a difficult work during the manufacturing process of the optical pickup unit 501 reduces the yield of the optical pickup unit 501, with the result that the price of the optical pickup unit 501 may rise.
An inadvertent shock to the housing 510 with which the optical pickup unit 501 is configured may cause the LD 540 or the so-called light emitting device 540 to disengage from the housing 510 with which the optical pickup unit 501 is configured.